Build Tower by the following given argument: number of floors (integer and always greater than 0).
Tower block is represented as *
Python: return a list; JavaScript: returns an Array; C#: returns a string[]; PHP: returns an array; C++: returns a vector; Haskell: returns a [String]; Have fun!
for example, a tower of 3 floors looks like below
[ ' * ', ' *** ', '*****' ]